Taking drops of allergens under the tongue can be an effective alternative to allergy shots for preventing coughing, wheezing and chest tightness common this time of year among allergy sufferers, according to a Johns Hopkins doctor's review of dozens of published studies.

The report, published on the Journal of the American Medical Association's website Wednesday, summarizes 63 studies and makes a case for what is known as sublingual immunotherapy. The treatment is popular in Europe but is less common in the United States. The Food and Drug Administration has not approved any applications from drug makers to use the treatment here.

The therapy uses the same mixes of allergens contained in allergy shots, which some allergy sufferers receive to prevent seasonal symptoms. But the research shows that drops can be an attractive alternative for those looking to avoid frequent injections.

"As opposed to medications that treat symptoms, [the therapy] has the potential to make patients' immune systems more tolerant, so it's actually changing some of the underlying problems," said Dr. Sandra Lin, the study's senior investigator, who also treats allergy patients at Johns Hopkins.

The cold-like allergy symptoms that come from what is known as allergic rhinitis affect 20 percent to 40 percent of the U.S. population. Prescription and over-the-counter drugs to treat the symptoms have become commonplace in pharmaceutical advertising campaigns.

For those seeking to prevent symptoms, allergy shots give patients gradually increasing dosages of allergens to strengthen their immune systems. The shots typically require a weekly or biweekly visit to a doctor's office for a period of a few years.

The under-the-tongue therapy uses the same theory and allergens but is less invasive.

In eight of 13 studies the Hopkins review examined, researchers found that the drops reduced allergy symptoms by 40 percent or more relative to other treatments, such as inhaled steroids. Nine of 36 other studies that compared the drops to treatments including antihistamines and nasal steroid sprays also found a 40 percent or greater reduction in symptoms.

Some of Lin's patients offer evidence of the therapy's effectiveness. Catonsville resident John Kapustka has dealt with severe spring and late-summer allergies for most of his 61 years, but after about four years of taking allergy drops, now hopes the symptoms may be behind him.

He has long taken antihistamines, and at around age 30 tried allergy shots until having one scary reaction to a dose. An avid hiker, he is eager to enjoy the outdoors without needing medication — something he was able to do last spring for the first time.

"I'm glad I can enjoy the outdoors and not think about, 'Oh, did I bring pills with me?'" Kapustka said. "So that's kind of nice."

Lin's research is part of a larger review of allergy immunotherapy treatments funded by the U.S. Agency for Healthcare Research and Quality.